This invention relates to antennas and more particularly to an improved reflex feed system for a dual frequency antenna.
It has been the custom to employ, with antennas transmitting dual frequencies, such as S-band and X-band frequencies, a dichroic plate for reflecting the S-band signals to the ellipsoidal reflector and cone of the S-band horn, while passing X-band signals to the X-band horn. It has been found that this dichroic plate causes two to three Kelvins noise temperature increase at the X-band frequency. Further, the dichronic plate must be separately mounted and aligned, requiring special installation and calibration procedures. It would be therefore, desirable to eliminate the plate, if possible.